Adjustable voltage divider circuit



April 1957 J. P. LINDLEY 3,315,152

ADJUSTABLE VOLTAGE DIVIDER CI RCUIT Filed April 13, 1965 IN VENTORUnited States Patent Ofiice 3,315,152 Patented Apr. 18, 1967 3,315,152ADJUSTABLE VOLTAGE DIVIDER CIRCUIT John P. Liudley, Redwood City,Calif., assignor to Zenith Radio Corporation, Chicago, Ill., acorporation of Delaware Filed Apr. 13, 1965, Ser. No. 447,613 8 Claims.(Cl. 32374) The invention is directed to an adjustable divider circuitand is particularly concerned with a circuit for achieving independentvoltage or current adjustment between the terminals of amultiple-terminal device, such as between the four electrodes of aquadrupole-type electron beam parametric amplifier.

The invention, while applicable to various multipleterminal dividers,was developed and will be described in conjunction with an electron beamparametric amplifier having a twisted quadrupole pump section. In suchdevices, opposite pairs of the four electrodes are maintained atdifferent voltages. The four electrodes are also maintained at anaverage voltage positive with respect to the cathode in the device.Because of manufacturing difliculties and tolerances, the quadrupoleelectrodes often are slightly displaced from their theoretically desiredpositions. To correct for this slight misplacement, the DC. bias an theparticular electrodes can be varied so as to alter the apparentpositions as seen by the electron beam. For ease in adjustment and setup, it is desirable that the individual bias adjustments can be achievedindependently.

It is a general object of the invention to provide a new and improvedmultiple-terminal divider circuit.

It is one specific object of the invention to provide a circuitpermitting independent adjustment of the average DC. potential on thequadrupole electrodes in an electron beam parametric amplifier whilealso allowing independent adjustment of the intrapair electrodepotentials and also allowing independent adjustment of the potentialbetween individual ones of the quadrupole electrodes.

It is another specific object of the invention to permit independentadjustment in the apportionment of'average current among four terminals,while also allowing independent adjustment of inter-terminalpair-apportioned current and independent adjustment of the apportionedcurrent as between individual ones of the terminals.

It is another object of the invention to provide a circuit capable ofachieving the foregoing but which is of simplified and economicalconstruction.

In one aspect, an adjustable divider circuit includes first, second,third, and fourth terminals. A first voltage divider is coupled betweenthe first and third terminals and a second voltage divider is coupledbetween the second and fourth terminals. A third voltage divider iscoupled between respective adjustable points on the first and secondvoltage divider. Four impedances are coupled individually at their oneends to respective ones of the four terminals and their other ends arecoupled in common. A source of adjustable potential is coupled betwen anadjustable point on the third voltage divider and the common ends of thefour impedances.

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The organizationand manner of operation of the invention, together with further objectsand advantages thereof, may best be understood by references to thefollowing description taken in connection with the accompanying drawing,in which the single figure is a partially schematic perspective view,partially broken away, of anelectron beam parametric amplifier tube andassociated circuitry constructed in accordance with the presentinvention.

Shown in the figure for the purpose of illustrating the presentinvention is a D.C.-pumped electron beam parametric amplifier tube. Itincludes an envelope 10 Within which is an electron gun 11 forprojecting a stream or beam of electrons along a path or axis 12 whichterminates in an electron beam collector 18. Electron gun 11 may beentirely conventional, including a cathode 11:: at ground potential andfocusing and accelerating electrodes 11b for defining the electron beam.Encircling envelope 10 at least over a portion of its length is asolenoid 13 which develops a homogeneous magnetic field H through whichthe electron beam is projected parallel to the flux lines. Solenoid 13establishes a condition of cyclotron resonance for the electrons.

An input-signal Cuccia coupler 14 is disposed first along the beam pathfollowing the electron gun. The application of input signal energy froma signal source 19, coupled across the electrodes of coupler 14, causesthe electrons to follow helical orbits along axis 12 with a periodicitydetermined by the strength of field H and with a radius proportional tothe .input signal amplitude.

Downstream from coupler 14 is a twisted-quadrupole D.C.-pumped type ofelectron motion expander 15. It is composed of a quadrifilar helix woundaround axis 12 with a pitch substantially equal to that of the electronorbits.

The quadrifilar helix has four electrodes 15a, 15b, 16a and 16b whichare twisted about beam path 12. In any cross section takenperpendicularly to path 12, the four quadrupole electrodes are at theend points of two diameters, disposed at a right angle to each other, ofa circle with its center on axis 12. Electrodes 15a and 15b are onopposite ends of one diameter while electrodes 16a and 16b are at theopposite ends of the other diameter. .The electrode pairs 15a, 15b or16a, 16b are so situated that the individual electrodes are sequentiallyspaced along the beam in the order: 15a, 16b, 15b, 16a.

Expander '15 subjects the electrons to a periodic inhomogeneous field.-In this instance, the field itself is static as seen by an externalobserver, but as viewed by the moving electron its polarity reversesfour times for every cyclotron orbit. That is, it defines a spatialperiodicity equal to twice the cyclotron resonance period.

Downstream from pump section 15 is an output Cuccia coupler 17 which inuse is coupled to a load 25. Coupler 17 operates inversely to inputcoupler 1-4 and extracts the amplified signal energy from the electronbeam.

The general operation of the electron beam parametric amplifier hereindisclosed and a more detailed description of its structure is containedin the co-pending application of Robert Adler, Ser. No. 326,737, filedNov. 29, 1963, and assigned to the same assignee as the presentapplication. As there fully discussed, the device preferably furth-erincludes means for producing a more intense magnetic field at thecathode in order to improve the signal-to-noise ratio. It will heresuffice to note that the orbiting electrons which leave input coupler 14are subjected, in twisted quadrupole 15, to field forces having theproper direction to cause additional energy to be imparted to the movingelectrons. In the particular case of the DC. pump illustrated, the DC.energy which effects translation of the electrons along beam path 12 isconverted by the inhomogeneous quadrupole field to rotational kineticenergy of the electrons. The higherenergy motion of the electrons isconverted to an output signal by coupler 17 and fed to load 25.

Each of the quadrupole electrodes is connected individually to oneterminal of an adjustable-divider network or circuit 26. In accordancewith the invention, circuit 26 is arranged to permit independentadjustment of the potential average on all terminals and on individualpairs of terminals as well as of the potentials on individual terminals.To this end, circuit 26 includes a source of adjustable voltage 30 oneside of which is connected to the center tap 31 of a voltage divider orpotentiometer 32. One end of potentiometer 32 is connected to the centertap 33 of a second potentiometer 34. The other end of potentiometer 32is connected to the center tap 35 of a third potentiometer 36. One endof potentiometer 34 is connected to terminal A, which in this embodimentis connected to electrode 15a, while the other end of potentiometer 34is connected to terminal 153 which in turn is connected to electrode15b. Similarly, one end of potentiometer 36 is connected to terminal 16Awhich in turn is connected to electrode 16a and the other end ofpotentiometer 36 is connected to terminal 16B which in turn is connectedto electrode 16b. Also connected respectively to each one of theterminals 15A, 15B, 16A, and 16B, and therefore coupled to each ofelectrodes 15a, 15b, 16a and 16b, is one end of equalvalue resistors37a, 37b, 37c and 37d. The other ends of resistors 37a, 37b, 37c and 37dare coupled in common to the other side of adjnstable voltage supply 30.

In operation, adjustment of voltage supply 30 determines the averagepositive voltage on the four quadrupole electrodes 15a, 15b, 16a and 16brelative to cathode 11a. Potentiometer 32 permits adjustment of the overall gain of the amplifier by setting the intraquadrupole pair voltage.Potentiometers 34 and 36 enable adjustment of the interelectrodepotential as necessary to compensate for any irregularities in electrodepositioning, thereby permitting the beam to be centered.

While circuit 26 has been depicted and described in conjunction with aDC. bias adjustment function, the invention contemplates applying thesame approach to any apparatus requiring independent potential orcurrent division among a plurality of terminals with a like number ofdegrees of freedom, whether the division is one of signals or of biases.For example, in a different embodiment potentiometers 32, 34- and 36 andresistors 37a, 37b, 37c and 37d may be replaced by reactive elements,such as capacitors or inductors, and voltage source 30 may be analternating-current signal source, without departing from the spirit ofthe invention.

The circuit described provides a flexible scheme of independentmulti-function potential or current adjustment. Yet, the circuit issimple and economical of construction. The concept is fully expandableto embrace a large number of terminals; this entails only the additionof further individual dividers according to the same pattern, analogousto enlarging the brackets for a singleelimination sporting meet.

While a particular embodiment ofthe invention has been shown anddescribed, it will be obvious to those skilled in the art that changesand modifications may be made without departing from the invention inits broader aspects and, therefore, the aim in the appended claims is to'cover all such changes and modifications as fall within the true spiritand scope of the invention.

I claim:

1. An adjustable-divider circuit comprising: first, second, third andfourth terminals;

a first voltage divider coupled between said first and third terminals;

a second voltage divider coupled between said second and fourthterminals;

a third voltage divider coupled between respective adjustable points onsaid first and second voltage dividers;

four impedances each of which is coupled individually to a respectiveone of said four terminals and the other ends of which are coupled incommon;

a source of adjustable potential coupled between an adjustable point onsaid third voltage divider and the common ends of said four impedances;and

utilization means coupled to and responsive to changes in potentials onsaid terminals.

2. A circuit for achieving independent adjustment of the average voltageon four terminals, independent adjustment of the average voltage on thefirst and second terminals with respect to the average voltage on thethird and fourth terminals, independent adjustment of the voltage onsaid first terminal with respect to said third terminal and independentadjustment of the voltage on said second terminal with respect to saidfourth terminal, comprising: means defining said four terminals;

a first voltage divider coupled between said first and third terminals;

a second voltage divider coupled between said second and fourthterminals;

a third voltage divider coupled between respective adjustable points onsaid first and second voltage dividers;

four impedances each of which is coupled individually to a respectiveone of said terminals and the other ends of which are coupled in common;

a source of adjustable potential coupled between an adjustable point onsaid third voltage divider and the common ends of said impedances; andutilization means coupled to and responsive to changes in potentials onsaid terminals.

3. An adjustable divider circuit comprising: first, second, third andfourth terminals;

a first voltage divider coupled between said first and third terminals;

2. second voltage divider coupled between said second and fourthterminals;

a third voltage divider coupled between respective adjustable points onsaid first and second voltage dividers;

four resistors of equal value each of which is coupled individually to arespective one of said terminals and the other ends of which are coupledin common;

a source of adjustable potential coupled between an adjustable point onsaid third voltage divider and the common ends of said resistors; andutilization means coupled to and responsive to changes in potentials onsaid terminals.

4. An adjustable-divider circuit comprising: first, second, third andfourth terminals;

an adjustable source of potential;

means coupled between one side of said source and two circuit points foradjustably apportioning the potential at said one side between said twopoints;

means coupled between one of said two points and said first and thirdterminals for adjustably apportioning the potential at said one pointbetween said first and third terminals;

means coupled between the other of said two points and said second andfourth terminals for adjustably apportioning the potential at said otherpoint between said second and fourth terminals;

means for coupling each of said terminals individually to the other sideof said source; and utilization means coupled to and responsive tochanges in potentials on said terminals.

5. An adjustable-divider circuit comprising: first, second, third andfourth terminals;

an adjustable source of potential;

means coupled between one side of said source and two circuit points foradjustably apportioning the potential at said one side between said twopoints;

means coupled between one of said two points and said first and thirdterminals for adjustably apportioning the potential at said one pointbetween said first and third terminals;

means coupled between the other of said two points and said second andfourth terminals for adjustably apportioning the potential at said otherpoint between said second and fourth terminals;

impedance means for coupling each of said terminals individually throughan impedance to the other side of said source; and utilization meanscoupled to and responsive to changes in potentials on said terminals.

6. An adjustable-divider circuit comprising: first, second, third andfourth terminals;

an adjustable source of current;

means coupled between one side of said source and two circuit points foradjustably apportioning the current at said one side between said twopoints;

means coupled between one of said two points and said first and thirdterminals for adjustably apportioning the current at said one pointbetween said first and third terminals;

means coupled between the other of said two points :and said second andfourth terminals for adjustably apportioning the current at said otherpoint between said second and fourth terminals;

impedance means for coupling each of said terminals individually throughan impedance to the other side of said source; and utilization meanscoupled to and responsive to changes in potentials on said terminals.

'7. An adjustable-divider circuit comprising: first, second, third andfourth terminals;

an adjustable voltage supply for varying the average voltage on saidfour terminals;

a first adjustable impedance coupled between said voltage supply andsaid terminals for varying the voltage on said first and secondterminals with respect to said third and fourth terminals;

a second adjustable impedance coupled between said first adjustableimpedance and said first and third terminals for varying the voltage onsaid first terminal with respect to said third terminal;

a third adjustable impedance coupled between said first adjustableimpedance and said second and fourth terminals for varying the voltageon said second terminal with respect to said fourth terminal;

fixed impedances coupled individually from each one 5 of said fourterminals to said voltage supply; and

utilization means coupled to and responsive to changes in potentials onsaid terminals.

*8. An intraquadrupole direct-current adjustment circuit comprising: anelectron beam tube having four quad- 10 rupole electrodes;

an adjustable voltage supply having two output terminals;

a first variable resistor having first, second .and third terminals thefirst of which is connected to one of said voltage supply outputterminals;

second and third variable resistors each having first, second and thirdterminals, the first terminals being respectively connected to thesecond and third terminals of said first variable resistor and thesecond and third terminals being respectively connected across differentspace-opposed pairs of said quadrupole electrodes;

and four fixed resistors individually connecting each one of saidquadrupole electrodes to the other output terminal of said voltagesupply.

A. D. PELLINEN, Assistant Examiner. 35

4. AN ADJUSTABLE-DIVIDER CIRCUIT COMPRISING: FIRST, SECOND, THIRD ANDFOURTH TERMINALS; AN ADJUSTABLE SOURCE OF POTENTIAL; MEANS COUPLEDBETWEEN ONE SIDE OF SAID SOURCE AND TWO CIRCUIT POINTS FOR ADJUSTABLYAPPORTIONING THE POTENTIAL AT SAID ONE SIDE BETWEEN SAID TWO POINTS;MEANS COUPLED BETWEEN ONE OF SAID TWO POINTS AND SAID FIRST AND THIRDTERMINALS FOR ADJUSTABLY APPORTIONING THE POTENTIAL AT SAID ONE POINTBETWEEN SAID FIRST AND THIRD TERMINALS; MEANS COUPLED BETWEEN THE OTHEROF SAID TWO POINTS AND SAID SECOND AND FOURTH TERMINALS FOR ADJUSTABLYAPPORTIONING THE POTENTIAL AT SAID OTHER POINT BETWEEN SAID SECOND ANDFOURTH TERMINALS; MEANS FOR COUPLING EACH OF SAID TERMINALS INDIVIDUALLYTO THE OTHER SIDE OF SAID SOURCE; AND UTILIZATION MEANS COUPLED TO ANDRESPONSIVE TO CHANGES IN POTENTIALS ON SAID TERMINALS.